This undated photo provided by Tom Smedinghoff, shows Anne Smedinghoff. Anne Smedinghoff, 25, was killed Saturday, April 6, 2013 in southern Afghanistan , the first American diplomat to die on the job since last year’s attack on the U.S. diplomatic installation in Benghazi, Libya. (AP Photo/Courtesy of Tom Smedinghoff)

CHICAGO (AP) — U.S. Secretary of State John Kerry stopped in Chicago on Monday to visit the parents of the young U.S. diplomat who was killed while delivering textbooks in southern Afghanistan earlier this month.

Kerry made the detour on his way back from Japan, the final leg of a 10-day overseas tour which started with tragedy when he learned of Anne Smedinghoff’s death while readying to depart for Turkey on April [auth] 6.

At the time, a clearly affected Kerry contacted Smedinghoff’s parents, Tom and Mary Beth, from Andrews Air Force Base. On Monday, he flew in directly to see them and Smedinghoff’s three siblings.

Smedinghoff was just 25 when she and four other Americans were killed while walking from a military base to a nearby school. Two explosions occurred, apparently a suicide car bombing followed by a roadside blast.

An FBI investigation is in its preliminary stages.

The diplomat’s father, Tom Smedinghoff, says the Kerry visit was only the latest by people in the U.S. diplomatic corps who reached out to the family.

“It really reinforces for us that Ann was part of a very close-knit family of very dedicated people who are serving our country,” he said.

Kerry told embassy staff in Tokyo that Smedinghoff was “full of idealism and full of hopes, taking books to children in a school so they can learn.”

She was “wiped out by terrorism — the worst kind of nihilism,” he said.

“It doesn’t stand for anything except killing people and stopping the future,” Kerry said. “And so we’re not going to be deterred. We’re going to be inspired. And we’re going to use Anne’s idealism as another motivation.”

Kerry declared the protection of American foreign service officers his top priority when started as secretary of state in February, and Smedinghoff’s death is the first of an American diplomat since militants attacked a U.S. diplomatic installation in Benghazi, Libya, on Sept. 11, killing Ambassador Chris Stevens and three other Americans.

The young woman’s death came just two weeks after Kerry met her while on a visit to Afghanistan. Smedinghoff served as his control officer, an honor often bestowed on up-and-coming members of the U.S. foreign service.

Smedinghoff, who grew up in River Forest, Ill., was on her second tour of diplomatic duty. She served previously in Venezuela.

The attack also killed three U.S. service members, a U.S. civilian who worked for the Defense Department and an Afghan doctor.

Three other diplomats were injured. The most serious is Kelly Hunt, a public diplomacy officer, who is being treated at a U.S. military base in Germany.